This invention generally relates to the treatment of largely aqueous effluents. In particular, it provides a method for removing various metal ions before waste effluents are released to the environment. Most particularly, the invention relates to removing and recovering chrome values from tanning effluents.
The aqueous effluents of many industries contain numerous metal ions. In the past, these wastes have been discharged to the environment with attendent harmful effects. Certain procedures are possible in treating such effluents. Ion exchange resins and zeolites might be used to remove the metal ions. Both of these materials are expensive and require large amounts of water, chemicals and energy for regeneration.
The treatment of animal hides by various chemical methods to produce leather requires the use of large amounts of water. Some efforts are made to recycle the water, but eventually, it must be discharged into the environment. Most tanneries employ chromium salts as tanning agents so that a major effluent contaminant is tri-valent chromium, usually called chrome. It is desirable to remove the chrome values from the effluent and preferably in a manner that they can be recovered easily.
In preparing this application, the fields of tanning, waste water treatment and adsorption by magnesium silicate were considered and searched. No relevant references were discovered, thereby no prior art references were considered in drafting this application.